Vegetation, such as lawns or horticultural crops, grown in areas where the soil structure prevents the ready absorption of moisture can result in excess irrigation water runoff due to water penetration becoming increasingly more difficult due to the sun's hardening of the soils surface and creating hydrophobic conditions in which the soil becomes unable to rapidly absorb water. As the soil becomes increasingly hydrophobic, the soil begins to repel much needed water from entering into the soil profile.
Vegetation, such as lawns or horticultural crops, grown in areas where the soil structure prevents or inhibits the retention of moisture can result in excess irrigation water requirements due to the water simply draining out of the soil profile too quickly, which results in need to constantly reapply moisture. This is typical of soils with high sand (quartz) content.
This can result in excessive use of water and potentially harmful run-off. The run-off can include plant nutrients, insecticides, fungicides, and herbicides, which can cause greater loss of crop productivity, and to the environment if such items are found in surface water reservoirs. Furthermore, this ineffective use of water can create higher demands on the water source used for irrigation.
During periods of drought, the lack of soil moisture results in plants undergoing moisture stress due to lack of soil moisture which will result in plant wilting, yield losses and ultimately death of the plant. At the same time this stress can increase the pathway for insect and disease infections and competition of more drought resistant weeds.
With respect to seed, seeds planted in soils that have characteristics outlined above, i.e. soils that are either hydrophobic or are unable to retain or have difficulty retaining moisture, can have their germination impeded, or they may require excessive watering to survive.
Soil wetting agents, or surfactants, are often introduced to the soil profile to help alleviate the issue of moisture absorption and/or retention of the soil, thereby increase the effectiveness of the water such that less is needed. Soil wetting agents work by lowering the cohesive and/or adhesive surface water tension and by absorbing and retaining water in the soil profile. This reduction of surface tension allows the water to spread out more evenly and allows for better penetration into the soils, and retention in the soil profile, including hydrophobic soils, or sandy soils, as well as more effective use of water.
Soil wetting agents can be polymer-based. These synthetic wetting agents are a relatively expensive product (compared to standard soil amendments), thereby possibly limiting their application, in addition polymers can over time degrade.
Naturally occurring clays have a natural affinity to water, and have a high water holding capacity. This is due to its extensive ability to bind water and to establish coherent structures in dry conditions. Clays, in addition to increasing water retention in soil, can provide plants with certain nutrients. Clays have been used as a wetting agent admixed with soils, such as described, for example, in U.S. Patent Application Publication No. 2010/0135733, and U.S. Pat. No. 4,810,280. However, prior art systems of admixing clays typically required large amounts of clay to be incorporated which is difficult and expensive to manufacture, require shipment of clay if the clay is not close at hand to the manufacturing site, or can cause dusting or attrition issues.
There remains a need for a readily-available source of clay variety, with a high water absorbing and retaining capacity, for use as a soil wetting agent with sufficient water holding capacity.